,  U.  s.  DEPARTMENT  OF  AGRICULTURE. 

BUREAU  OF  ENTOMOLOGY— BULLETIN  No.  56. 

L.   O.    HOWARD,   Entomolo 


THE  BLACK  HILLS  BEETLE, 


KTI1KR  NOTES  ON  ITS  DlSTKliirTION,  LT/EiLHISlMlUV. 
AND  METHODS  OF  CONTWH. 

X 

— 

\UKI>  UNDER  THE  DIRECTION  OF  THE  ENTOMOLOGIST. 


a   ,-.  ln>,-^WW,^  \\i\VU\'A 


WASHINGTON: 

-     G  O  V  F.  It  N  M  E  N  T     I'KIN'TI  X  Q     OFFICE. 

1  it  0  5 . 


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BUREAU  OF  EX  TOKOLOGY. 

L.  O.  Howard,  Entomologist  and  Chief  of  Bv  nan. 

C  L.  Marlatt,  Entomologist  and  Acting  Chief  in  absents  of  Chief, 

R.  S.  Cliftox,  Chief  Clerk. 

F.  H.  Chittenden,  in  charge  of  breeding  experiments. 
A.  D.  Hopkins,  in  charge  of  forest  insect  investigations. 
W.  D.  Hunter,  in  charge  of  cotton  boll  weevil  invesfigtioris. 

F.  M.  Webster,  in  charge  of  cereal  and  forage-phi  nt  insect  investigations. 
A.  L.  Quaixtance,  in  charge  of  deciduous-fruit  insect  investigations. 
Frank  Benton,  in  charge  of apicultural  investigations. 

E.   A.   Schwarz,     D.    W.   Coquillett,    Tu.    Pergande»    Xatiiax     Banks.    .1 

Entomologists. 
E.  S.  0.  Trrcrs,  Aoatrsr  Busck,  Otto  Heidemanx,  A.  X.  Caudell.  K.  1'.  Currxe,  i   (1. 

Sanders,  F.  D.  Coudex,  E.  R.  Sasscer,  J.  II.  Beattie,  I.  J.  Condit,  Assistants. 
R.  C.  Althouse.  W.  F.  Tastet.  Mam  (1.  Ciiampxey,  A.  J.  Leister,  E.  C.  Wood,  T.  A. 

Keleher,  Jessie  E.  Marks,  Stenographers  and  Clerks. 
Lillian  L.  Howenstein.  Artist 
Mabel  Colcord,  Librarian. 

H.  E.  Burke,  W.  F.  Fiske,  J.  L.  Webb.  J.  F.  Strauss,  engaged  in  forest  insect  investigations. 
W.  E.  Hinds,  A.  W.  Morrill,  Springer  Goes,  J.  C.  Crawford,  W.  A.  Hooker,  W.  W 

Yothers.  A.  C.  Morgan.  W.  D.  Pierce.  F.  C  Bishopp,  C.  R.  Jones.  R.  C.  Howell, 

F.  C.  Pratt,  C.  E.  Sanborn,  engaged  in  cotton  boll  weevil  invest igai 

G.  I.  Reeves.  W.  J.  Phillips,  engaged  in  cereal  and  forage-plant  n  ligations. 
Fred.  Johnson,  A.  A.  Girault,  engaged  in  deciduous-fruit  insect  investigations. 

E.  F.  Phillips.  J.  M.  Rankin,  Leslie  Martin,  engaged  in  apicultural  investigations. 
C.  J.  Gilliss,  W.  A.  Keleher,  engaged  in  silk  investigations. 


U.  S.  DEPARTMENT  OF  AGRICULTURE. 

BUREAU  OF  ENTOMOLOGY— BULLETIN  No.  56. 

L.   O.    HOWARD,    Entomologist. 


THE  BLACK  HILLS  BEETLE, 


WITH 


FURTHER  NOTES  ON  ITS  DISTRIBUTION,  LIFE  HISTORY, 
AND  METHODS  OF  CONTROL. 


OF   THE 

PREPARED  UNDER  THE  DIRECTION  OF  THE  ENTOMOLOGIST. 


,;•„..;(  ,.JL  fi.  flOPK&B Bh :  D 0   PI       •  1 


Case. 


WASHINGTON: 

GOVERNMENT    PRINTING     OFFICE, 

1905. 


LETTER  OE  TRANSMITTAL. 


U.  S.  Department  of  Agriculture, 

Bureau  of  Entomology, 
Washington,  D.  C,  November  14,  190-5. 
Sir:  I  transmit  herewith  the  manuscript  of  the  report  of  Dr. 
A.  D.  Hopkins,  of  this  Bureau,  on  an  investigation  of  the  Black  Hills 
beetle,  with  especial  reference  to  its  occurrence  in  the  Pikes  Peak 
Forest  Reserve  and  in  the  vicinity  of  Colorado  Springs  and  Palmer 
Lake.     This  investigation  was  made  at  the  request  of  the  Bureau 
of  Forestry,  and  I  recommend  the  publication  of  the  report,  which 
brings  the  information  concerning  this  species  up  to  date,  as  Bulletin 
56  of  this  Bureau.     The  figures  and  plates  are  necessary  for  the 
illustration  of  the  text. 
Respectfully, 

L.  O.  Howard, 
Entomologist  and  Chief  of  Bureau. 
Hon.  James  Wilson, 

Secretary  of  Agriculture. 


CONTENTS. 


Page. 

Introductory 5 

Historical  references 5 

Report  on  forest  insect  investigation  in  the  Pikes  Peak  Forest  Reserve 8 

Objects 8 

Explorations - 9 

Summary  of  results,  conclusions,  and  recommendations 9 

The  Black  Hills  beetle 10 

Characters  of  the  beetle 11 

Characters  of  the  gallery 11 

Characters  of  the  infested  trees 13 

Life  history 15 

Natural  and  artificial  influences 16 

Drought  and  cold 16 

Lightning 16 

Storms 16 

Fire 16 

Commercial  cutting ' 17 

Summer  cutting  in  patches 17 

Trap  trees 17 

Natural  enemies 18 

Insects 18 

Birds 18 

Diseases  of  insects 18 

Secondary  enemies  of  the  trees,  and  neutral  insects 18 

Methods  of  control 19 

Application  of  the  method  in  the  Black  Hills 19 

Application  of  the  method  in  Colorado 20 

Further  recommendations  relating  to  the  control  of  the  beetle 21 

Note 22 

Index 23 

3 


ILLUSTRATIONS 


Page. 
Plate    I.  Work  of  the  Black  Hills  beetle.     Fig.  1. — Primary  galleries  and  larval 
mines  in  inner  bark.     Fig.  2. — Marks  of  primary  galleries  on  surface 

of  scoring  chip 12 

II.  Work  of  the  Black  Hills  beetle.  Fig.  1. — Marks  of  primary  galleries  on 
surface  of  wood  when  bark  is  removed.  Fig.  2. — Freshly  attacked 
tree,  showing  pitch  tubes;  adjoining  tree  not  attacked 14 

TEXT   FIGURES. 

Fig.  1.  The  Black  Hills  beetle:  adult 11 

2.  Work  of  the  Black  Hills  beetle:  primary  galleries  and  larval  mines  in  inner 

surface  of  living  bark 12 

3.  Work  of  the  Black  Hills  beetle,  in  inner  bark  of  dead  tree 13 

4.  Work  of  the  Black  Hills  beetle:  pitch  tubes  on  surface  of  bark 14 

5.  The  Black  Hills  beetle:  larva 15 

6.  The  Black  Hills  beetle:  pupa 15 

4 


THE  BLACK  HILLS  BEETLE. 

{Dendroctouus  ponder oscea  Hopk.) 


INTRODUCTORY. 

The  object  of  this  bulletin  is  to  give  additional  information  on 
the  distribution,  life  history,  habits,  and  methods  for  the  control 
of  the  Black  Hills  beetle,  based  on  further  investigations  by  the 
writer  and  his  field  assistants,  and  information  through  correspond- 
ence with  forest  officials  and  others. 

It  is  now  known  that  this  beetle  occurs  in  the  eastern  sections  of 
the  Rocky  Mountain  region  from  the  Black  Hills  of  South  Dakota 
to  northern  New  Mexico;  and  there  is  evidence  that  its  distribution 
extends  westward  into  Utah  and  northern  Arizona. 

It  attacks  and  kills  the  western  yellow  or  bull  pine  (Pinus  pon- 
derosa)  and  the  white  spruce  (Picea  canadensis)  in  the  Black  Hills 
of  South  Dakota;  and  the  western  yellow  or  bull  pine,  the  limber 
pine  {Pinus  flexilis),  and  the  Engelmann  spruce  (Picea  engelmanni) 
in  the  Pikes  Peak  region. 

Wherever  this  insect  is  found  in  abnormal  numbers  its  depreda- 
tions on  living  timber  are  more  or  less  extensive.  It  has  killed 
between  700,000,000  and  1,000,000,000  feet  of  timber  in  the  Black 
Hdls  Forest  Reserve,  and  is  also  demonstrating  its  destructive 
powers  in  central  Colorado  and  New  Mexico. 

The  method  for  its  control  recommended  by  the  writer  and 
adopted  in  the  Black  Hills  and  Pikes  Peak  region  has  been  suffi- 
ciently tested  to  show  that  it  is  both  practicable  and  effective,  and 
that,  under  proper  management,  a  forest  can  be  protected  at  a 
moderate  expenditure,  or  almost  without  cost  where  there  is  a 
market  for  the  timber. 

HISTORICAL  REFERENCES. 

Probably  the  earliest  published  information  on  the  destructive 
work  of  this  insect  is  that  by  Prof.  H.  S.  Graves,6  in  which  he  refers 
to  the  dying  pine  timber  in  the  Black  Hills  of  South  Dakota.  He 
stated  that  the  patches  of  dying  and  dead  timber  are  usually  rec- 
tangular in  shape,  following  the  tops  of  the  divide  or  ridges  and 
running  lengthwise  up  and  down  the  slope,  and  that  this  injury  was 
probably  caused  by  bark-boring  insects  of  a  species  of  Scolytidae. 

a  Family  Scolytidae.  6  Ninth  Rept.  U.  S.  Geol.  Surv.,  Pt.  V,  p.  87,  1897-98. 

5 


D  THE    BLACK    HILLS    BEETLE. 

Specimens  of  the  bark-boring  insects  found  attacking  the  living 
trees  in  the  area  mentioned  by  Professor  Graves  were  sent  to  the 
Department  of  Agriculture  in  August,  1898,  by  Mr.  William  M.  Pratt, 
from  Piedmont,  S.  Dak.,  and  by  Mr.  H.  E.  Dewey,  from  Lead,  S.  Dak., 
and  more  specimens"  were  sent  in  by  Mr.  Dewey  in  August,  1899. 
These  were  at  first  identified  as  Dendroctonus  rufipennis  Kirby,  and 
as  D.  terebrans  Oliv. ;  but  in  1900  they  were  examined  by  the  writer 
and  were  found  to  represent  an  undescribed  species  of  Dendroctonus. 
Specimens  of  the  same  insect  were  also  found  in  the  collections  of  the 
American  Entomological  Society,  at  Philadelphia,  and  in  the  United 
States  National  Museum,  labeled  South  Dakota,  Utah,  and  Colorado, 
the  latter  from  Pikes  Peak,  July  10,  1900. 

In  September,  1901,  upon  the  request  of  Mr.  Gifford  Pinchot, 
Chief  of  the  Bureau  of  Forestry,  and  under  the  direction  of  Dr. 
L.  O.  Howard,  Chief  of  the  Division  of  Entomology,  an  investiga- 
tion of  the  trouble  affecting  the  timber  in  the  Black  Hills  Forest 
Reserve  was  made  by  the  writer;  and  on  October  23,  1901,  a  type- 
written report  was  submitted  to  Doctor  Howard  and  Mr.  Pinchot 
which,  with  additional  data  and  illustrations,  was  transmitted  for 
publication  in  January,  1902,  and  was  issued  in  that  year  as  Bulletin 
No.  32,  new  series,  of  the  Division  of  Entomology.  In  this  bulletin 
the  new  species  found  to  be  the  primary  cause  of  the  death  of  the 
timber  was  described  under  the  name  of  Dendroctonus  ponderosse, 
and  certain  facts  in  its  habits  and  life  history  were  presented, 
together  with  recommendations  based  thereon,  for  felling  and  barking 
the  infested  trees  at  a  time  of  the  'gear  when  the  mere  removal  of  the  bark 
from  the  main  trunk,  without  burning,  would  be  sufficient  to  kill  the 
broods. 

In  July,  1902,  Mr.  John  P.  Brown,  secretary  of  the  International 
Society  of  Arboriculture,  issued  a  "Special  Rocky  Mountain  Bulletin 
on  the  Destructive  Beetles  of  Pinus  ponderosa,"  in  which  reference  is 
made  to  the  destruction  of  pine  timber  in  the  Black  Hills  of  South 
Dakota  and  in  Colorado  by  two  beetles,  which  he  designates  as  the 
"large  destructive  barkbeetle"  and  the  "small  destructive  bark- 
beetle,"  but  he  omitted  their  scientific  or  technical  names.  There- 
fore it  is  not  known  to  what  particular  species  he  referred,  or  whether 
or  not  he  had  two  or  more  species  confused.  It  is  evident,  however, 
that  the  depredations  in  the  Black  Hills  were  caused  by  D.  ponderosse, 
previously  described. 

Mr.  Brown  recommended  the  remedy  of  felling  and  barking  the 
trees  and  burning  the  bark  with  the  tops ;  but  his  main  argument  was 
for  the  protection  of  insectivorous  birds. 

In  1902  Mr.  J.  L.  Webb,  special  field  agent  in  forest  insect  investi- 
gations, assigned  from  the  Bureau  of  Forestry,  and  working  under 
instructions  from  the  writer,  spent  five  months  (May  28-October  30) 


THE    BLACK    HILLS    BEETLE.  ( 

in  the  Black  Hills  Reserve,  studying  the  life  history  and  habits  of  the 
beetle.  He  also  conducted  extensive  trap-tree  experiments,  in  which 
over  two  hundred  matured  healthy  trees  were  girdled  or  felled  to 
determine  their  attractive  influence  on  the  Black  Hills  beetle  and 
other  forest-tree  insects.  In  August,  1902,  and  June,  1903,  the 
writer  visited  the  reserve  and  made  special  studies  of  the  beetle  and 
of  the  trap-tree  experiments.  In  October  and  November,  1902,  and 
November,  1904,  Field  Assistant  H.  E.  Burke  visited  the  reserve  for 
the  same  purpose,  and  Forest  Ranger  W.  G.  Courtney  made  records 
of  observations  on  the  trap  trees  from  June  to  October,  1903. 

August  12,  1902,  Prof.  C.  P.  Gillette  sent  specimens  of  a  barkbeetle 
from  Bailey,  Colo.,  with  a  statement  that  he  had  found  it  in  dying 
pine  trees.  This  proved  to  be  the  Black  Hills  beetle,  I),  ponderosx, 
and  was  the  first  authentic  record  of  its  work  in  Colorado. 

During  a  special  investigation  in  May,  1903,  the  writer  found  the 
same  species  in  northwestern  New  Mexico,  in  the  vicinity  of  Vermejo, 
where  it  was  attacking  and  killing  the  matured  pine  timber  over  a 
large  area.  Here  the  method  of  cutting  and  barking  the  infested 
trees  was  recommended. 

In  December,  1904,  specimens  of  the  beetle  were  sent  by  Mr.  P.  P. 
Blass,  with  a  statement  that  a  large  amount  of  timber  was  dying  in 
the  vicinity  of  Palmer  Lake.  In  reply,  Mr.  Blass's  attention  was 
called  to  the  dangerous  character  of  this  enemy  of  pine  trees,  and 
pubhshed  data  on  the  subject,  supplemented  by  written  instructions 
for  the  cutting  and  barking  of  infested  trees,  were  sent  him.  Upon 
the  suggestion  of  Mr.  Blass,  on  February  15,  1905,  a  set  of  bulletins 
and  written  instructions  were  also  sent  to  the  town  board  of  Palmer 
Lake.  This  resulted  in  the  cutting  and  barking  of  a  large  number 
of  infested  trees  by  different  people  in  that  vicinity.  Upon  infor- 
mation from  the  clerk  of  the  town  board  of  Palmer  Lake  that  the 
timber  was  dying  in  the  forest  reserve,  adjoining  the  town  property, 
information  was  conveyed  by  the  writer  to  the  Forest  Service,  to- 
gether with  copies  of  recommendations  for  the  cutting  and  barking 
of  infested  timber;  also  stating  that  upon  receipt  of  information  from 
the  supervisor  as  to  the  character  and  extent  of  the  trouble  in  the 
reserve,  the  Bureau  of  Entomology  would  take  the  matter  up  with 
them  and,  if  necessary,  send  a  man  into  the  field  to  make  special 
investigations.  Later  a  report  of  May  11,  1905,  addressed  to  the 
Forest  Service  by  Supervisor  Clarke,  was  referred  to  the  writer  on 
May  17.  In  reply  to  this,  more  detailed  instructions  were  sent  to 
Supervisor  Clarke,  for  the  identification  of  the  trees  which  should  be 
cut,  with  the  statement  that  it  would  be  more  desirable  for  the 
Bureau  to  make  an  investigation  in  the  fall. 

In  a  letter  dated  July  14,  1905,  Prof.  C.  P.  Gillette,  State  ento- 
mologist of  Colorado,  stated  that  during  a  visit  to  Palmer  Lake  he 


8  THE   BLACK    HILLS    BEETLE. 

noted  that  a  large  amount  of  timber  was  d}ring  in  that  vicinity. 
The  specimens  sent  to  the  Bureau  of  Entomology  with  his  letter 
proved  to  be  the  Black  Hills  species,  thus  leaving  no  doubt  regarding 
the  primary  enemy  and  the  great  danger  of  an  invasion  which  might 
soon  extend  beyond  control  unless  active  measures  were  adopted. 

In  the  meantime,  General  Palmer,  certain  members  of  the  faculty 
of  the  Colorado  College,  and  others  interested  in  the  protection  of  the 
forests  in  the  vicinity  of  Colorado  Springs  had  inaugurated  an  active 
campaign  to  control  the  ravages  of  the  beetle,  in  which  the  services  of 
Prof.  Lawrence  Bruner,  of  the  University  of  Nebraska,  were  secured 
to  make  investigations  and  give  instructions  in  felling  and  barking 
the  timber.  Two  reports  were  submitted  by  Professor  Bruner  to 
General  Palmer,  one  dated  August  2,  the  other  September  19.  These 
reports,  together  with  correspondence  and  other  data,  were  published 
in  Arboriculture  for  October,  1905,  pages  205-212. 

Under  Professor  Bruner's  direction  between  600  and  800  trees 
on  private  lands  in  the  vicinity  of  Glen  Eyrie,  Colorado  Springs,  and 
adjoining  the  reserve  were  felled  during  August,  September,  and 
October,  and  the  bark  removed  and  burned  with  the  tops,  to  kill  the 
insects  with  which  they  were  infested. 

On  September  16  a  full  report  of  the  results  of  explorations  by 
the  forest  rangers  in  the  Pikes  Peak  Forest  Reserve  was  submitted  to 
the  Chief  of  the  Forest  Service  by  Supervisor  Clarke.  This  included 
specified  descriptions  of  ranges  and  sections  containing  infested 
timber  which  General  Palmer  had  requested  permission  to  cut  and 
bark  at  his  own  expense,  for  the  further  protection  of  the  surrounding 
public  and  private  forests.  Copies  of  these  typewritten  reports 
and  statements  were  submitted  by  the  Acting  Forester  for  consid- 
eration, and  upon  consultation  with  Mr.  Gifford  Pinchot,  Forester, 
and  Mr.  Overton  W.  Price,  Associate  Forester,  it  was  decided  that 
the  writer  should  proceed  at  once  to  make  the  necessary  investiga- 
tion on  which  to  base  recommendations  for  the  consideration  of 
forest  officials  and  others,  in  further  efforts  to  control  the  destruc- 
tive insects  in  and  around  the  Pikes  Peak  Reserve. 

This  investigation  was  made  October  5  to  13,  1905,  and  the  fol- 
lowing report  submitted : 

REPORT    ON   FOREST    INSECT    INVESTIGATIONS    IN   THE  PIKES 
PEAK  FOREST  RESERVE. 

OBJECTS. 

The  object  of  this  special  trip  was  to  investigate  the  character  and 
extent  of  depredations  by  the  pine-destroying  beetle  of  the  Black 
Hills  (Dendroctonus  ponderosse  Hopk.)  in  the  pine  forests  of  the  Pikes 
Peak  Forest  Reserve,  in  the  vicinity  of  Colorado  Springs  and  Palmer 


THE    BLACK    HILLS    BEETLE.  9 

Lake  and  at  such  other  points  as  might  be  deemed  necessary;  to  give 
instructions  to  the  forest  officials  and  others  in  carrying  out  our  rec- 
ommendations for  the  control  of  this  and  other  insects  directly 
associated  with  the  dying  timber,  and  to  determine  for  the  Forest 
Service  the  approximate  extent  of  necessary  cutting  of  timber  on  the 
reserve  to  protect  the  remaining  living  timber  in  the  vicinity  of  Col- 
orado Springs  and  adjoining  private  estates,  as  proposed  by  Gen. 
William  J.  Palmer. 

EXPLORATIONS. 

Beginning  on  the  morning  of  October  5  explorations  were  made  as 
follows:  Glen  Eyrie  trail  on  mountain  northward,  returning  via 
Douglass  Canyon;  October  6,  from  Glen  Eyrie  by  way  of  Colorado 
City,  Bear  Creek  Canyon,  High  Line  road,  to  Bruin  Inn,  returning  by 
way  of  North  Chej^enne  Canyon,  Colorado  Springs,  and  Palmer  Park; 
October  7,  from  Glen  Eyrie  by  way  of  Manitou,  over  Crystal  Park 
trail  to  Crystal  Park,  returning  by  the  Bear  Creek  trail,  Bear  Creek 
Canyon,  and  Colorado  Springs;  October  8,  from  Glen  Eyrie,  by  way 
of  Blair  Athol,  Pike  View,  Pope  Ranch,  and  Palmer  Park;  Octo- 
ber 9,  from  Colorado  Springs  byway  of  Colorado  Springs  and  Cripple 
Creek  Railway  to  Clyde,  thence  by  wagon  to  an  altitude  of  about 
10,000  feet,  returning  by  same  route  to  Colorado  Springs;  October 

10,  from  Colorado  Springs  by  way  of  the  Colorado  Midland  Rail- 
road to  Woodland  Park,  thence  by  wagon  to  Manitou  Park;  October 

1 1 ,  by  saddle  from  Manitou  Park  east  to  Palmer  Lake,  thence  by 
wagon  southeast  by  way  of  Husted  to  Woodland  Ranch;  October 

12,  in  the  Colorado  pinery  on  the  Arkansas  and  Platte  divide;  Octo- 
ber 13,  in  the  Colorado  pinery,  returning  by  way  of  Colorado  Springs 
to  Glen  Eyrie. 

Additional  explorations  were  made  on  the  12th  and  13th  by  Mr. 
Edmonston,  under  my  instructions,  in  the  vicinity  of  Palmer  Lake. 

During  all  but  one  of  these  trips  I  was  accompanied  by  Mr.  W.  D. 
Edmonston,  head  ranger  of  the  Pikes  Peak  Forest  Reserve,  who  was 
designated  by  Forest  Supervisor  Clarke  as  the  proper  official  to 
receive  instructions  in  the  identification  of  the  infested  trees  to  be 
felled  and  barked  to  kill  the  principal  insect  enemies.  I  was  also 
accompanied  on  a  number  of  the  trips  by  General  Palmer's  foreman, 
who  received  similar  instructions.  Supervisor  Clarke  accompanied 
us  on  two  trips,  General  Palmer  on  three,  and  Forest  Assistant 
Clement  on  two. 

SUMMARY  OF  RESULTS,  CONCLUSIONS  AND  RECOMMENDATIONS. 

(1)  The  depredations  by  the  Black  Hills  beetle  (Dendroctonus 
ponderosx  Hopk.)  within  the  area  examined  are  by  no  means  as 
extensive  as  we  were  led  to  believe  from  the  reports  and  correspond- 
ence. 

12405— No.  56—06 2 


10  THE    BLACK    HILLS    BEETLE. 

(2)  The  principal  areas  of  recent  damage  by  this  beetle  in  the 
reserve  and  on  private  lands  are  in  the  vicinity  of  Cascade  and 
Palmer  Lake ;  but  evidence  of  old  and  new  work  was  observed  to  be 
more  or  less  frequent  in  all  sections  visited. 

(3)  The  evidence  found  on  old,  dead,  standing,  and  felled  trees  of 
the  work  of  the  Black  Hills  beetle  on  pine,  the  spruce-destroying 
beetle  {Dendroctonus  piceaperda  Hopk.)  on  Engelmann  spruce,  and 
the  Douglas  spruce  Dendroctonus  (D.  pseudotsugx  Hopk.  MSS.)  on 
Douglas  spruce  indicate  that  all  of  these  species  have  been  present  and 
destructive  to  living  timber  in  this  region  for  at  least  fifty  years. 
The  number  and  distribution  of  such  old  beetle-marked  trees  indi- 
cate that  very  extensive  depredations  have  been  wrought  by  them 
in  the  Pikes  Peak  region  within  the  past  century;  and  present 
conditions  also  indicate  that  a  large  per  cent  of  the  vast  destruction 
of  timber,  heretofore  attributed  to  fire,  was  primarily  due  to  the 
work  of  these  insects. 

(4)  The  three  species  of  bark  beetles  above  mentioned  are  without 
doubt  the  most  important  insect  enemies  of  conifer  forests  in  the 
central  Rocky  Mountain  region;  hence  they  are  a  constant  menace 
to  the  remaining  living  timber  in  and  around  the  reserves  of  central 
Colorado. 

While  at  present  the  spruce-destroying  beetle  appears  to  be  rare, 

and  the  Douglas  spruce  and  Black  Hills  beetles  are  not  common 

enough  to  cause  extensive  depredations,  it  is  plain,  from  what  is 

known  of  the  destructive  powers  of  these  insects,  that  if  neglected 

and  if  specialty  favorable  conditions  for  their  multiplication  should 

prevail  for  two  or  more  years  in  succession  they  could  easily  destroy 

all  of  the  timber  of  commercial  size  and  a  large  per  cent  of  the 

reproduction. 

THE  BLACK  HILLS  BEETLE. 

The  Black  Hills  beetle  (D.  ponderosse)  is  at  present  the  most  com- 
mon and  destructive  enemy  of  the  living  pine  timber  in  and  around 
the  Pikes  Peak  Reserve;  therefore  it  should  receive  primary  con- 
sideration. 

The  best  success  in  any  efforts  by  forest  officials  or  private  owners 
of  forests  to  control  this  beetle  will  depend  on  a  sufficient  knowledge 
of  the  species,  its  habits,  life  history,  and  the  influences  which  are 
favorable  or  unfavorable  for  its  increase  and  destructive  invasions. 

Insufficient  knowledge  on  these  points  results  in  the  confusion  of 
the  primary  and  secondary  enemies  of  the  tree,  unnecessary  expendi- 
ture of  time  and  money,  by  felling  and  barking  trees  at  the  wrong 
time  of  the  year,  or  after  the  broods  of  the  primary  enemy  have 
emerged,  the  felling  of  living  trees  which  would  have  recovered, 
and  the  unnecessary  destruction  of  beneficial  insects  and  insect  dis- 
eases by  burning  the  bark. 


THE    BLACK    HILLS    BEETLE. 


11 


The  following  description  of  distinctive  characters  of  the  beetle, 
its  work,  habits,  life  history,  etc.,  is  based  on  the  results  of  our 
studies  of  the  species  in  the  field  and  laboratory,  brought  up  to  date, 
regardless  of  what  has  been  previously  published  or  given  out  in 
correspondence. 

CHARACTERS    OP   THE    BEETLE   (FIG.   1). 

The  distinctive  characters  of  the  Black  Hills  beetle  are  its  length, 
which  is  from  one-sixth  to  one-fourth  of  an  inch;  its  stout  form, 
with  broad  head  and  pro  thorax;  its  black  color,  and  the  rounded 
or  convex  rear  end  of  the  body  (declivity  of  the  elytra),  which  is 
without  conspicuous  long  hairs.  The  allied  species,  which  may  be 
mistaken  for  it,  are  distinguished  as  follows:  The  large  red  turpen- 
tine beetle  (Dendroctonus  valens  Lee.)  is  much  larger,  is  dark  reddish 
in  color,  never  black,  and  forms  large 
masses  of  pitch  at  or  toward  the  base  of 
living  and  dying  pine  trees  and  stumps. 
The  Colorado  Dendroctonus  (D.  approxi- 
mate Dietz)  is  black,  with  broad  head, 
but  the  body  is  more  elongate,  the  front 
of  the  head  is  grooved,  and  the  declivity 
of  the  elytra  has  long,  stiff  hairs;  it  lives 
in  the  bark  of  pine,  but  makes  a  winding, 
sometimes  branched,  gallery.  The  spruce- 
destroying  beetle  (Dendroctonus  piceaperda 
Hopk.)  is  reddish  brown  to  black,  but  with 
much  narrower  head,  with  long  hairs  on  the 
declivity  of  the  elytra,  and  is  always  found 
in  spruce.  The  Douglas  spruce  beetle 
(Dendroctonus  pseudotsugse  n.  sp.)  is  dark  red  or  brown,  and  always 
breeds  in  Douglas  spruce  and  western  larch.  The  species  which  most 
closely  resembles  the  Black  Hills  beetle  is  the  mountain-pine  beetle 
(Dendroctonus  monticola  Hopk.),  which  is  only  distinguished  in  the 
adult  stage  by  the  smaller  size,  slightly  less  stout  form,  less  dis- 
tinctly roughened  elytra,  and  more  obscured  rows  of  punctures  on 
the  sides  of  the  elytra,  the  latter  being  the  most  important  char- 
acter for  its  distinction. 

CHARACTERS   OF   THE    GALLERY   (FIGS.    2    AND    3   AND   PL.    i). 

The  primary  gallery  excavated  in  the  bark  by  the  Black  Hills 
beetle  is  distinguished  from  that  of  any  other  species  as  yet  known 
to  hive  in  the  pine  of  the  Black  Hills  or  Colorado  by  the  slight  curve 
at  the  entrance  end  and  the  almost  straight  course  with  the  grain 
through  the  inner  layers  of  bark,  and  grooving  the  surface  of  the 
wood.     There  is  only  one  pine-infesting  species  with  which  this  form 


Fig.  1.— The  Black  Hills  beetle:  o, 
adult,  enlarged;  b,  same,  natural 
size.     (Author's  illustration.) 


12 


THE    BLACK    HILLS    BEETLE. 


of  gallery  can  be  confused,  namely,  the  mountain  pine  beetle,  which 
has  not  as  yet  been  found  in  the  same  region.  If  it  should  occur, 
however,  the  galleries  may  be  distinguished  by  the  smaller  size,  more 


Fig.  2.— Work  of  the  Black  Hills  beetle  (Dendroctonus  ponderosx  Hopk).  Primary  galleries  and 
larval  mines  in  inner  surface  of  living  bark:  a,  entrance  and  basal  chamber;  6,  ventilating  holes  in 
roof  of  gallery;  e,  termination.  The  larval  mines  radiate  from  the  primary  galleries.  About  one- 
half  natural  size.     (Author's  illustration.) 

crooked  and  slightly  winding  course,  and  by  the  fact  that  they  are 
more  commonly  met  with  in  the  silver  pine,  limber  pine,  and  lodge- 
pole  pine.     Whenever  the  Black  Hills  species  is  found  in  spruce  the 


THE    BLACK    HILLS    BEETLE. 


13 


gallery  is  distinguished  from  that  of  the  spruce-destroying  beetle  by 
its  slender  form  and  more  evenly  distributed  side  or  brood  mines. 

CHARACTERS    OF    THE    IXFESTED    TREES    (FIG.  4   AND    PL.    Il) . 

Trees  attacked  by  the  Black  Hills  beetle  between  July  and  October 
will  be  indicated  by  the  presence  of  pitch  tubes,  or  sawdust  borings, 
and  upon  removal  of  the  bark  the  young  broods  will  be  found  mining 
through  the  inner  living  layers,  or  the  bark  will  be  entirely  killed  on 
the  main  trunk;  but  the  foliage  will  remain  green,  or  will  be  but 
faintly  faded  until 
May  and  June  of 
the  following  year, 
when  the  leaves  on 
the  lower  branches 
will  turn  yellow  and 
die.  This  condition 
will  rapidly  extend 
to  the  topmost 
leaves,  so  that  by 
the  time  the  broods 
of  maturing  beetles 
are  ready  to  emerge 
the  foliage  is  yel- 
lowish red  to  light 
reddish  brown  in 
color.  This  is  the 
stage  of  death  called 
"sorrel  tops." 
Later  in  the  sum- 
mer and  during  the 
following  winter, 
after  all  living  ex- 
amples OI  the  beetle  piG  3  _Work  of  tne  Black  Hi]ls  Deetle,  in  inner  bark  of  dead  tree: 
have  emerged,  the  a,  primary  galleries;  6,  larval  mines;  c,  pupal  chambers;  d,  exitholes. 
fnliacrp    i«  Hark  rprl-       Reduced  about  one-half .     (Author's  illustration.) 

dish  brown,  caUed  "red  tops."  This  condition  prevails  during  the 
second  summer  after  attack;  but  by  the  third  summer  all,  or  nearly 
all,  of  the  leaves  have  fallen,  which  gives  the  tops  of  the  dead  trees  a 
blackish  appearance,  called  "black  tops." 

Beginning  with  freshly  attacked  trees  during  the  first  summer, 
they  are  distinguished  by  the  exudation  of  fresh  whitish  or  reddish 
pitch  forming  small  masses  or  tubes  on  the  bark  of  the  main  trunk 
or  by  the  presence  of  fresh  reddish  sawdust-like  borings  lodged  in 
the  loose  bark  and  around  the  base  of  the  tree. 


14 


THE    BLACK    HILLS    BEETLE. 


Trees  infested  with  partially  to  fully  developed  broods  from  the 
latter  part  of  August  to  the  first  of  November,  and  during  the  period 
of  inactivity,  are  distinguished  by  numerous  pitch  tubes  over  and 
entirely  around  the  middle  portion  of  the  trunk  and  extending  more 

or  less  toward  the  base  and 
top.  The  age  of  the  pitch 
tubes  is  indicated  by  their 
relatively  moist  or  dry  con- 
dition. A  successful  or  vital 
infestation  will  be  sbown  by 
the  large  number  of  pitch 
tubes  surrounding  the  entire 
trunk,  and  also  by  their  red- 
dish color  and  general  ap- 
pearance. An  unsuccessful 
attack — from  which  the  tree 
will  recover — is  indicated 
after  the  first  of  November 
by  a  small  number  of  smooth 
whitish  pitch  masses  scat- 
tered about  over  the  trunk, 
confined  to  or  toward  the 
base ;  their  absence  on  the 
middle  to  upper  portion  of 
the  trunk  or,  if  present  there, 
their  failure  to  completely 
surround  it. 

Positive  evidence  as  to 
whether  or  not  a  green- 
topped,  pitch-marked  tree  is 
infested  by  living  broods  is 
determined  only  by  cutting 
into  the  bark  at  different 
places,  4  to  8  feet  from  the 
base.  This  test  should  be 
made  during  the  inactive 
period,  when  trees  are  being 
marked  for  cutting. 

Soon  after  activity  begins 
in  the  spring,  infested  trees 
are  distinguished  by  a  pale  appearance  of  the  foliage,  followed  by  a 
yellow  or  reddish  brown  color,  as  if  killed  by  fire. 

Dead  trees  which  have  been  killed  by  the  Black  Hills  beetle  but 
are  no  longer  infested  by  living  broods  are  distinguished  during  the 
summer,  fall,  and  winter  by  the  old  dry  pitch  tubes  on  the  bark  and 
the  dark  reddish  brown  or  "black-topped"  condition.     The  only 


Fig.  4— Work  of  the  Black  Hills  beetle:  a,  pitch  tubes  on 
surface  of  bark,  much  reduced;  b,  same,  two-thirds 
natural  size.     (Author's  illustration.) 


Bui.  56,  Bureau  of  Entomology,  U.  S.  Dept.  of  Agriculture. 


Plate  II. 


THE    BLACK    HILLS    BEETLE. 


15 


exception  to  this  is  when  the  top  portion  of  the  tree  or  one  side  of 
the  trunk  is  killed  the  first  year  and  a  brood  develops  in  the  remain- 
ing living  bark  the  next  year.  This  sometimes  occurs,  but  is  never 
common  enough  to  require  special  notice.  Its  occasional  occurrence, 
however,  explains  why  broods  of  the  beetle  are  sometimes  found  in 
trees  which  appear  to  have  been  dead  for  two  or  tliree  years. 

LIFE  HISTORY. 

The  insect  passes  the  winter,  or  inactive  period,  in  all  stages — as 
larvae,  pupae,  and  adults — beneath  the  bark  of  trees  attacked  by 
the  parent  beetles  during  the  previous  summer 
and  fall.  Activity  begins  in  the  spring  as  soon  as 
sufficient  warm  weather  prevails,  when  the  broods 
continue  to  develop  and  mature,  but  remain  in  the 
bark  until  about  the  middle  of  July  (Black  Hills, 
latitude  44°,  altitude  7,000  feet),  probably  later 
northward  and  at  higher  altitudes,  and  earlier 
southward  and  at  lower  altitudes.  When  the 
adults  (fig.  1)  begin  to  emerge  from  the  bark  of  the 
trees  in  which  they  had  developed  from  eggs  depos- 
ited the  previous  year,  they  usually  fly  in  swarms, 
and  attack  the  living  trees,  in  which  they  excavate 
galleries  through  the  inner  layer  of  bark  and  groove  FlG  5._Larva  of  the 
the  surface  of  the  wood.  Along  the  sides  of  these 
primary  galleries  excavated    by  the    beetle,  eggs 

are  deposited  for  the  next  generation,  which,  as  be- 
fore, hatch  into  grubs  or  larvae  (fig.  5),  which  mine  at 
right  angles  to  the  primary  galleries  through  the  inner 
bark,  on  which  they  feed.  This  feeding  and  growing 
stage  continues  during  the  first  summer,  some  of  the 
individuals  completing  their  development  before  fall, 
so  that  all  stages,  including  the  pupa?  (fig.  6) ,  may  be 
found  during  the  fall  in  the  trees  attacked  in  July. 
These  with  the  younger  broods  remain  dormant  dur- 
ing the  winter  and  complete  their  development  the 
following  spring  in  time  to  emerge  in  their  regular 
course  during  the  following  summer. 

The  period  of  flight  of  the  beetles  and  of  their  attack 
on  living  trees,  as  well  as  the  egg-depositing  period,  is 
about  seventy-five  days,  beginning  about  the  middle 
of  July  and  ending  about  the  first  of  October.  The  exact  time  of 
the  beginning  and  ending  of  this  period  in  a  given  locality  depends 
upon  the  latitude,  altitude,  and  local  conditions.  The  normal 
period  of  development  of  a  brood  from  the  time  the  living  tree  is 
attacked  and  the  eggs  deposited  until  the  adults  emerge  from  the 


Black      Hills      beetle. 
(Author's  illustration.) 


FlG.  6  —  Pupa  of  the 
Black  Hills  beetle. 
(Author's  illus- 
tration.) 


16  THE    BLACK    HILLS    BEETLE. 

dying  or  dead  trees  is  about  three  hundred  and  forty  days.  The 
period  of  activity — the  feeding,  growing,  and  maturing  stages — of 
all  broods  of  a  single  generation  during  the  first  summer  is  about 
ninety  days — July  15  to  October  15 — and  about  one  hundred  and 
fifty  days  from  the  time  activity  begins  the  following  spring — early 
in  May — until  the  last  individual  has  developed  and  emerged-  early 
in  October.  Thus  there  is  a  total  active  period  of  about  two  hundred 
and  forty  days.  The  period  of  inactivity — from  about  October  15 
to  early  in  May — is  about  one  hundred  and  ninety-five  days,  making 
the  total  period  of  infestation  of  all  broods  of  a  single  generation 
about  four  hundred  and  thirty-five  days.  This,  of  course,  provides 
for  an  overlapping  of  the  last  broods  of  one  generation  and  the  first 
broods  of  the  next,  during  July,  August,  and  September. 

NATURAL  AND  ARTIFICIAL  INFLUENCES. 

DROUGHT   AND    COLD. 

It  has  been  a  common  belief  that  the  dying  of  the  timber  is  caused 
by  drought,  but  it  is  now  clearly  demonstrated  that  wherever  the 
Black  Hills  beetle  is  abundant  it  kills  the  healthiest  trees  under  all 
conditions  of  dn*  and  wet  seasons,  moist  or  dry  soils,  north  or  south 
slopes,  ridges,  etc.  It  has  also  been  demonstrated  that  it  can  with- 
stand a  temperature  of  30°  to  40°  F.,  or  more,  below  zero. 

LIGHTNING. 

It  has  been  found  that  trees  struck  by  lightning,  or  at  least  those 
struck  in  summer,  are  usually  attacked  by  this  beetle,  and  that 
such  trees  serve  to  perpetuate  the  species  at  times  when  it  does 
not  occur  in  sufficient  numbers  to  kill  trees  on  its  own  account. 
Such  trees  also  serve  to  support  the  natural  enemies  of  the  beetle, 
including  insects,  diseases,  and  birds. 

STORMS. 

Storm-felled  living  trees  also  serve  as  emergency  breeding  places, 
and  if  the  storm  occurs  at  the  proper  time  in  the  year  to  make  the 
conditions  especially  attractive  to  the  beetles  when  they  are  flying, 
they  may  be  attracted  for  long  distances.  This  concentration  of 
scattering  forces  breeding  in  felled  timber  may  form  the  nucleus  for 
a  destructive  invasion.  This  has  been  demonstrated  from  time  to 
time  in  Europe,  where  even  secondary  enemies  of  the  genus  Tomicus 
have  been  thus  enabled  to  multiply  in  such  great  numbers  as  to 
attack  and  kill  living  forests. 

FIRE. 

Our  observations  so  far  have  failed  to  reveal  much  evidence  that 
this  species  will  breed  in  trees  injured  or  killed  by  fire  in  sufficient 


THE    BLACK    HILLS    BEETLE.  17 

numbers  to  materially  aid  their  increase.  Indeed,  newly  fire- 
scorched  trees  observed  near  a  sawmill  in  the  Manitou  Park  section 
showed  no  trace  of  the  presence  or  work  of  this  beetle,  although  the 
trees  were  being  attacked  by  several  species  of  secondary  enemies, 
including  the  true  turpentine  beetle  {Dendroctonus  valens  Lee.)-  On 
the  other  hand,  an  extensive  forest  fire  may  contribute  to  the  destruc- 
fcion  of  the  Black  Hills  beetle  by  burning  the  dead  bark  from  the  liv- 
ing and  dying  infested  trees,  which  may  explain  the  evident  sudden 
endings  of  old  invasions. 

COMMERCIAL    CUTTING. 

The  cutting  of  living  trees  for  commercial  purposes  has  appar- 
ently little  or  no  influence  on  the  multiplication  of  the  beetle.  While 
it  will  breed  hi  freshly  cut  logs  from  living  trees,  our  experiments 
show  that  it  prefers  to  attack  standing  timber.  Then,  again,  any 
operations  which  involve  the  removal  of  the  bark  from  the  logs  for 
ties,  mining  timbers,  etc.,  will  destroy  any  broods  which  may  be 
therein.  If  cut  into  cord  wood,  the  bark  will  soon  become  too  dry 
for  the  insect  to  live  in.  Slabs  from  freshly  cut  logs  may  favor  its 
development  in  small  numbers,  but  usually  the  conditions  in  such 
material  are  not  favorable.  Neither  do  the  green  stumps,  so  far 
as  we  have  observed,  offer  sufficiently  attractive  breeding  places 
for  tins  beetle  to  warrant  the  barking  of  such  stumps.  Nothing  in  the 
slash  will  offer  favorable  breeding  places,  except  the  tops  of  the  main 
trunk,  and  this  is  seldom  sufficient  to  warrant  any  special  treatment. 

SUMMER    CUTTING    IN    PATCHES. 

The  cutting  of  living  infested  trees  and  of  healthy  trees  in  local 
commercial  cuttings  is  objectionable  from  the  fact  that  we  have 
found  that  when  a  few  living  trees  are  felled  in  the  midst  of  a  forest 
where  this  beetle  is  present  in  numbers  it  will  be  attracted  by  the 
odor  and  will  attack  the  surrounding  standing  timber.  Therefore 
such  local  summer  cuttings  should  be  avoided. 

TRAP    TREES. 

This  is  a  method  of  combating  bark  beetles  in  which  trees  are 
girdled  or  felled  to  attract  the  insects  to  them,  after  which  the  broods 
are  destroyed  by  stripping  off  the  bark  or  burning  the  entire  tree. 

Trap-tree  experiments  were  conducted  by  Mr.  J.  L.  Webb,  under 
the  writer's  instructions,  in  the  Black  Hills  Keserve  in  1902,  in  which 
trees  were  felled,  hack  girdled,  girdled  to  the  heartwood,  belt  girdled, 
and  hacked  and  peeled  at  intervals  of  five  or  six  days  between  June 
2  and  October  30.  The  result  of  this  experiment  showed  conclu- 
sively that  no  method  of  preparing  the  trap  trees  was  of  sufficient 


18  THE    BLACK    HILLS    BEETLE. 

value  in  its  attractive  influence  on  the  Black  Hills  beetle  to  warrant 
its  adoption  in  efforts  to  control  this  insect.  While  many  of  the 
trap  trees  were  attacked,  the  percentage  and  density  of  the  infesta- 
tion were  no  greater  than  in  near-by  or  distant  healthy  trees.  On 
the  other  hand,  it  was  shown  conclusively  that  the  felled  trap  trees 
were  especially  attractive  to  one  of  the  most  important  secondary 
enemies,  namely,  the  Oregon  Tomicus  {Tomicus  oregoni  Eichh.). 

NATURAL  ENEMIES. 
IXSECTS. 

While  a  number  of  insect  enemies  of  the  Black  Hills  beetle  have 
been  found  during  our  investigations,  they  appear  to  have  little  effect 
when  the  timber  is  dying  over  large  areas,  but  under  normal  condi- 
tions of  scattering  infested  trees  they  seem  to  render  valuable  serv- 
ice in  preventing  the  rapid  multiplication  of  the  destructive  beetle. 

BIRDS. 

The  work  of  woodpeckers  is  frequently  seen  on  infested  trees,  but, 
like  the  beneficial  insects,  they  do  their  greatest  service,  perhaps, 
in  helping  to  preserve  the  normal  balance  in  the  struggle  of  the  trees 
against  insects  and  of  the  insects  against  their  own  enemies. 

DISEASES    OF    IXSECTS. 

Evidence  was  frequently  found  of  the  destruction  of  part  or  all  of 
the  broods  in  an  infested  tree  by  fungous  diseases,  but  to  what 
extent  this  factor  affects  the  decrease  of  the  beetle  has  not  been 
determined. 

SECONDARY  ENEMIES  OF  THE  TREES,    AND   NEUTRAL  INSECTS. 

Insects  which  attack  only  weakened,  dying,  or  dead  trees,  and 
those  associated  with  a  destructive  or  primary  enemy  are  called  sec- 
ondary enemies.  Insects  which  simply  live  under  the  bark  or  feed 
on  fungi,  dead  wood,  and  bark  are  in  no  manner  responsible  for 
injury  to  the  tree.  Thus  they  are  either  neutral  insects,  scavengers, 
or  guests. 

There  are  so  many  of  all  of  these  classes  of  insects  associated  with 
the  Black  Hills  beetle  in  trees  killed  by  it  that  it  would  require  too 
much  space  to  discuss  them  in  this  connection;  but  it  seems  neces- 
sary to  say  that  the  greatest  care  should  be  taken  to  avoid  confusing 
some  of  the  species  of  secondary  enemies  with  the  primary  one,  and 
that  when  there  is  the  slightest  doubt  specimens  should  be  sent  to 
this  Bureau  for  identification. 


THE    BLACK    HILLS    BEETLE.  19 

METHODS  OF  CONTROL. 

The  results  of  our  investigations  to  date  suggest  but  slight  changes 
in  our  recommendations  in  1901  and  1902,  published  in  Bulletin  32 
(pp.  21,  22),  as  follows: 

It  appears  that  the  pine-destroying  beetle  of  the  Black  Hills,  like  its  eastern  relatives, 
depends  on  the  trees  killed  by  it  for  the  augmentation  of  its  numbers  and  the  perpetuation 
of  its  power  of  killing  more  trees.  Therefore  it  is  only  necessary  that  the  attacking  force  be 
reduced  to  a  point  where  it  can  no  longer  overcome  the  vital  resistance  of  the  trees  on  which 
it  concentrates  its  attack  in  order  to  successfully  defeat  it. 

The  fact  that  the  attacking  force  of  the  enemy  is  already  weakened  from  natural  agencies 
suggests  that  they  can  be  reduced  by  artificial  means  below  their  power  of  killing  more  trees 
next  season,  and  thus  bring  the  trouble  to  an  end.  Therefore  the  following  are  suggested 
and  recommended  as  probably  the  best  methods  of  accomplishing  this  result: 

(1)  Determine  the  location  and  extent  of  areas  in  which  trees  were  attacked  during  the 
summer  and  fall  (of  1901)  and  the  number  of  trees  now  infested  with  living  broods  of  the 
pine-destroying  beetle. 

(2)  Select  those  areas  in  which  there  are  the  largest  number  of  infested  trees  and  mark 
the  same  for  cutting. 

(3)  Secure,  by  sale  contracts  or  otherwise,  the  cutting  of  these  trees  and  the  removal  of 
the  bark  from  the  infested  parts  of  the  main  trunks  and  stumps  prior  to  May  1  ( 1902).  The 
drying  of  the  removed  infested  bark  and  surface  of  the  wood  will  effectually  destroy  the 
insects.  In  addition  the  logs  so  treated  will  be  protected  next  spring  and  summer  from  the 
attack  of  wood-boring  insects,  and  thus  be  almost  or  quite  as  valuable  for  all  commercial 
purposes  as  if  cut  from  living  trees. 

It  is  not  necessary  that  all  infested  trees  in  the  reserve  or  those  of  all  other  infested  areas 
should  be  thus  cut  and  barked,  but  it  is  important  that  a  large  percentage  should  be  so 
treated  in  order  to  insure  a  sufficient  reduction  of  the  beetles  to  check  their  destructive 
ravages. 

Experience  has  shown  quite  conclusively  that  the  above  recom- 
mendations are  entirely  practicable,  and  it  has  also  been  demon- 
strated that  whenever  the  felled  trees  are  accessible  for  lumber,  ties, 
mining  timbers,  or  cord  wood  it  can  usually  be  sold  for  more  than  the 
cost  of  cutting  and  barking. 

APPLICATION  OF  THE  METHOD  IN  THE  BLACK  HILLS. 

There  has  been  a  continued  effort  to  control  this  destructive  beetle 
in  the  Black  Hills  Reserve  since  1901,  but  the  adoption  of  the  neces- 
sary radical  measures  was  prevented  by  certain  regulations  governing 
the  management  of  the  reserve,  which  required  the  advertising  and 
sale  of  the  old  dead  and  dying  timber,  for  which  there  was  not  a  suffi- 
cient demand  in  the  State  of  South  Dakota;  and  since  a  special  pro- 
vision of  the  law  prohibited  the  shipment  of  timber  out  of  the  State, 
it  was  practically  impossible  to  accomplish  anything  of  importance. 

We  are  informed,  however,  that  the  evident  benefit  in  certain  sec- 
tions resulting  from  cutting  and  barking  the  infested  timber  is  such 
as  to  indicate  that  if  more  radical  measures  had  been  adopted  under  a 
more  liberal  policy  of  timber  sales,  and  under  a  temporary  amend- 


20  THE    BLACK    HILLS    BEETLE. 

ment  of  the  laws  relating  to  its  shipment  out  of  the  State,  the 
destructive  beetle  could  have  been  brought  under  complete  control 
and  millions  of  feet  of  valuable  timber  saved  without  cost  to  the 
Government. 

APPLICATION  OF  THE  METHOD  IN  COLORADO. 

Pursuant  to  our  recommendations,  a  large  number  of  trees  were 
felled  during  the  past  summer  (1905)  on  private  lands  in  and  around 
Palmer  Lake,  Colorado,  where  between  500  and  1,000  trees  had  been 
killed  within  recent  years  over  a  comparatively  small  area.  Observa- 
tions by  the  writer  in  October,  and  explorations  by  Ranger  Edmon- 
ston  in  that  vicinity,  indicated  a  xery  slight  new  infestation  this  year. 
It  is  evident,  therefore,  that  the  efforts  of  the  town  board  and  of  the 
citizens  in  cutting  and  barking  the  infested  trees  has  had  the  desired 
effect  in  partially,  if  not  completely,  checking  the  destructive  work  of 
the  beetle.  If  tins  good  work  is  supplemented  with  a  like  effort  on 
the  part  of  forest  officials  during  the  coming  winter,  there  is  every 
reason  to  believe  that  the  trouble  in  this  vicinity  will  be  brought  under 
complete  control,  and  that  with  a  little  well-directed  effort  each  suc- 
ceeding year  it  can  be  kept  within  normal  bounds. 

The  same  method  was  adopted  by  General  Palmer  and  others,under 
the  direction  of  Professor  Bruner,  in  the  vicinity  of  Colorado  Springs 
and  the  Colorado  pinery  on  the  Platte  and  Arkansas  Divide.  The 
operation  of  barking  and  felling  the  affected  dead  and  dying  trees 
extended  over  an  area  of  probably  150,000  acres,  and  between  600  and 
800  trees  were  felled  and  barked,  and  the  bark  burned  with  the  tops. 

A  thorough  examination  of  this  area  by  the  writer  indicates  quite 
conclusively  that  the  forces  of  the  enemy  have  thus  been  sufficiently 
weakened  to  make  their  complete  subjugation  a  comparatively  easy 
matter,  especially  if  the  principal  areas  of  present  infestation  in  the 
reserve  receive  the  proper  treatment  between  now  and  the  first  of 
May. 

It  is  evident  to  the  writer  that  in  both  localities  considerable  unnec- 
essary expense  was  involved  in  the  cutting  of  old  dead  trees  from 
which  the  enemy  may  have  escaped  and  of  those  which  might  have 
recovered,  as  well  as  in  burning  the  bark  and  tops,  peeling  the  stumps, 
etc.;  but  it  is  plain  that  the  losses  from  such  unnecessary  expen- 
ditures are  of  little  consequence  as  compared  with  the  great  good 
accomplished. 


THE    BLACK    HILLS    BEETLE.  21 

FURTHER  RECOMMENDATIONS*  RELATING   TO   THE    CONTROL  OF 

THE  BEETLE. 

(1)  Explorations  should  be  made,  preferably  during  August,  Sep- 
tember, and  October,  to  locate  the  principal  areas  of  new  infestation. 

(2)  Mark  for  cutting  all  clumps  or  patches  of  infested  trees  and 
some  of  the  more  accessible  scattering  ones  in  the  worst-infested 
sections. 

(3)  The  best  time  to  fell  and  bark  infested  trees  is  between  the 
middle  of  October  and  the  first  of  May. 

(4)  If  there  is  no  demand  for  the  timber,  and  more  can  be  accom- 
plished by  piling  the  trunks  and  tops  and  burning  them,  or  sufficiently 
scorching  the  bark  to  kill  the  insects,  this  method  may  be  followed; 
but  barking  the  infested  portion  of  the  trunks,  without  burning  the 
bark  or  tops,  is  preferable,  since  it  will  avoid  the  destruction  of  many 
beneficial  insects,  and  the  exposed  broods  of  the  destructive  beetle 
furnish  food  for  birds. 

(5)  In  some  localities,  and  under  certain  conditions,  it  may  be 
advisable  to  burn  the  tops,  but  if  this  is  done  to  kill  the  insects  it 
should  be  delayed  until  after  the  first  of  May  and  completed  before 
the  middle  of  June. 

(6)  If  for  any  reason  the  work  of  felling  and  barking  the  trees  can 
not  be  undertaken  or  completed  before  the  first  of  May,  it  may  be  done 
during  May  and  June.  The  necessity  for  burning  the  bark  and  tops 
at  such  time  will  depend  upon  local  conditions  and  requirements. 

(7)  Summer  operations  should  be  avoided.  There  is  nothing  to  be 
gained  in  felling  freshly  attacked  trees  which  can  just  as  well  be  cut  in 
the  fall  and  winter.  In  addition,  there  is  danger  of  the  freshly  felled 
and  barked  trees  exerting  an  attractive  influence  on  the  swarms  of 
beetles  which  will  cause  them  to  attack  the  surrounding  living  timber. 
Then,  again,  any  burning  operations  during  the  summer  involves  the 
danger  of  starting  forest  fires. 

(8)  If  it  is  especially  desirable,  on  account  of  timber  sale  and 
logging  contracts,  to  cut  the  old  dead  as  well  as  the  newly  infested 
living  trees  during  the  active  period  of  the  insect — May  to  October — 
a  thorough  exploration  should  be  made  by  a  forest  entomologist  or  a 
trained  forester,  who  should  be  responsible  for  the  marking  of  the 
infested  living  trees.  It  is  also  important  that  all  cutting  of  infested 
timber  be  concentrated  in  the  worst  affected  localities. 

(9)  The  burning  of  summer  slash  and  the  barking  of  stumps  of 
trees  which  are  healthy  when  felled  is  not  necessary  as  a  preventive 
measure  against  the  Black  Hills  beetle,  and  the  necessity  for  doing  so 
against  any  other  insect  depends  entirely  on  the  species  involved  and 
local  conditions. 


22  THE    BLACK    HILLS    BEETLE. 

(10)  The  result  of  experiments  and  observations  indicate  that  the 
trap-tree  method  can  not  be  successfully  adopted  for  this  insect. 

(11)  If  a  large  amount  of  pine  timber  is  blown  down  at  any  time, 
but  especially  in  June  and  July,  it  should  be  carefully  watched  during 
the  first  year  or  two  to  determine  whether  or  not  it  is  attacked  b}'  the 
Black  Hills  beetle,  and,  if  so,  the  bark  should  be  removed  during  the 
fall  after  the  attack  is  made. 

NOTE. 

The  statements  in  this  bulletin  under  the  headings  of  "Life  His- 
tory," "Natural  and  Artificial  Influences,''  and  "Methods  of  Con- 
trol" relate  to  the  Black  Hills  beetle  alone  and  are  not  applicable  to 
any  other  species  of  barkbeetle. 


INDEX. 

Page. 

Adult,  character 11 

Attack,  influences  aiding  or  inducing 16 

Birds  as  natural  enemies 18 

Cold,  as  affecting  infestation 16 

Colorado  Dendroctonus,  distinguishing  characters 11 

Control,  in  Black  Hills 19-20 

in  Colorado. 20 

methods 19,  21 

Damage,  extent 5 

Dendroctonus  approximates,  distinguishing  characters 11 

Colorado.     See  Dendroctonus  approximates. 
Douglas  spruce.     See  Dendroctonus  pseudotsugse. 

monticola,  distinguishing  characters 11 

piceaperda,  distinguishing  characters 11 

work  in  dead  Engelmann  spruce 10 

ponderosse — subject  of  this  bulletin. 

pseudotsugse,  distinguishing  characters 11 

in  western  larch 11 

work  in  dead  Douglas  spruce 10 

rujipennis,  wrong  determination 6 

terebrans,  wrong  determination 6 

valens,  attacking  fire-scorched  trees 17 

distinguishing  characters 11 

Destructiveness 5 

Development,  time  required 16 

Diseases 18 

Distribution 5 

Douglas  spruce,  attacked  by  Dendroctonus  pseudotsugse. 10 

Dendroctonus.    See  Dendroctonus  pseudotsugse. 

Drought ,  as  affecting  infestation 16 

Eggs,  time  of  depositing 15 

Enemies,  insect 18 

Fire,  as  affecting  infestation 16 

Food  plants 5 

Fungous  diseases 18 

Gallery,  character 11 

Infested  trees,  indications  of  attack 13 

Larch,  western,  attack  of  Dendroctonus  pseudotsugse 11 

Larvae,  diseases 18 

habits 15 

Life  history 15 

23 


24  INDEX. 

Lightning,  as  cause  of  infestation ,fi 

Mountain-pine  beetle.     See  Dendrodonus  monticola. 

Natural  enemies .  „ 

Neutral  insects 

Oregon  Tomicus.     See  Tomicus  oregoni. 

Parasitic  enemies .  R 

Picea  canadensis,  attack  of  Dendrodonus  ponderosse 5 

engdmanni,  attack  of  Dendrodonus  ponderosse 

Pine,  bull.  See  Pinus  ponderosa. 
limber.  See  Pinus  flexilis. 
western  yellow.     See  Pinus  ponderosa. 

Pinus  flexilis,  attack  of  Dendrodonus  ponderosse 5 

ponderosa,  attack  of  Dendrodonus  ponderosse 5 

Pitch  tubes 

Predaceous  enemies .  0 

Remedial  measures.     See  Control. 

Secondary  enemies  of  trees •■  s 

Spruce,  Douglas,  attack  of  Dendrodonus  pseudotsugse 10 

Engelmann.     See  Picea  engdmanni. 

attack  of  Dendrodonus  piceaperda 10 

See  also  Picea  engdmanni. 
white.    See  Picea  canadensis. 
Spruce-destroying  beetle.    See  Dendrodonus  piceaperda. 

Storm-felled  trees,  inducing  infestation ig 

Temperature,  as  affecting  infestation ifi 

Tomicus  oregoni,  attack  on  trap  trees jg 

Oregon.     See  Tomicus  oregoni. 

Trap  trees -  ]7 

Turpentine  beetle,  large  red.    See  Dendrodonus  valens. 


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UNIVERSITY  OF  FLORIDA 


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